Synopsis

Description

The tset utility sets up your terminal, typically when you first log
in. It does terminal dependent processing such as setting erase and kill
characters, setting or resetting delays, sending any sequences needed to properly initialized
the terminal, and the like. tset first determines the type of terminal
involved, and then does necessary initializations and mode settings. If a port
is not wired permanently to a specific terminal (not hardwired) it is
given an appropriate generic identifier such as dialup.

reset clears the terminal settings by turning off CBREAK and
RAW modes, output delays and parity checking, turns on NEWLINE translation, echo
and TAB expansion, and restores undefined special characters to their default state.
It then sets the modes as usual, based on the terminal
type (which probably overrides some of the above). See stty(1) for more
information. All arguments to tset may be used with reset. reset also
uses rs= and rf= to reset the initialization string and file.
This is useful after a program dies and leaves the terminal in
a funny state. Often in this situation, characters do not echo as
you type them. You may have to type LINEFEED reset LINEFEED since RETURN
may not work.

When no arguments are specified, tset reads the terminal type from the
TERM environment variable and re-initializes the terminal, and performs initialization of mode,
environment and other options at login time to determine the terminal type
and set up terminal modes.

When used in a startup script (.profile for sh(1) users or .login
for csh(1) users) it is desirable to give information about the type
of terminal you usually use on ports that are not hardwired. Any
of the alternate generic names given in the file /etc/termcap are possible identifiers.
Refer to the -m option for more information. If no mapping applies
and a final type option, not preceded by a -m, is given
on the command line then that type is used.

It is usually desirable to return the terminal type, as finally determined
by tset, and information about the terminal's capabilities, to a shell's environment.
This can be done using the -, -s, or -S options.

For the Bourne shell, put this command in your .profile file:

eval `tset -soptions...`

or using the C shell, put these commands in your .login file:

set noglob
eval `tset -s options...`
unset noglob

With the C shell, it is also convenient to make an alias
in your .cshrc file:

alias ts 'eval `tset -s \!*`'

This also allows the command:

ts 2621

to be invoked at any time to set the terminal and environment.
It is not possible to get this aliasing effect with a Bourne
shell script, because shell scripts cannot set the environment of their parent.
If a process could set its parent's environment, none of this nonsense
would be necessary in the first place.

Once the terminal type is known, tset sets the terminal driver mode.
This normally involves sending an initialization sequence to the terminal, setting the
single character erase (and optionally the line-kill (full line erase)) characters, and
setting special character delays. TAB and NEWLINE expansion are turned off during transmission
of the terminal initialization sequence.

On terminals that can backspace but not overstrike (such as a CRT),
and when the erase character is `#', the erase character is changed
as if -e had been used.

Options

-

The name of the terminal finally decided upon is output on the standard output. This is intended to be captured by the shell and placed in the TERM environment variable.

-ec

Set the erase character to be the named character c on all terminals. Default is the BACKSPACE key on the keyboard, usually ^H (CTRL-H). The character c can either be typed directly, or entered using the circumflex-character notation used here.

-ic

Set the interrupt character to be the named character c on all terminals. Default is ^C (CTRL-C). The character c can either be typed directly, or entered using the circumflex-character notation used here.

-I

Suppress transmitting terminal-initialization strings.

-kc

Set the line kill character to be the named character c on all terminals. Default is ^U (CTRL-U). The kill character is left alone if -k is not specified. Control characters can be specified by prefixing the alphabetical character with a circumflex (as in CTRL-U) instead of entering the actual control key itself. This allows you to specify control keys that are currently assigned.

-n

Specify that the new tty driver modes should be initialized for this terminal. Probably useless since stty new is the default.

-Q

Suppress printing the `Erase set to' and `Kill set to' messages.

-r

In addition to other actions, reports the terminal type.

-s

Output commands to set and export TERM. This can be used with

set noglob
eval `tset -s . . .`
unset noglob

to bring the terminal information into the environment. Doing so makes programs such as vi(1) start up faster. If the SHELL environment variable ends with csh, C shell commands are output, otherwise Bourne shell commands are output.

-m [ port-ID [ baudrate ] :type ] . . .

Specify (map) a terminal type when connected to a generic port (such as dialup or plugboard) identified by port-ID. The baudrate argument can be used to check the baudrate of the port and set the terminal type accordingly. The target rate is prefixed by any combination of the following operators to specify the conditions under which the mapping is made:

>

Greater than.

@

Equals or at.

<

Less than.

!

It is not the case that (negates the specified operators).

?

Prompt for the terminal type. If no response is given, then type is selected by default.

In the following example, the terminal type is set to adm3a if the port is a dialup with a speed of greater than 300 or to dw2 if the port is a dialup at 300 baud or less. In the third case, the question mark preceding the terminal type indicates that the user is to verify the type desired. A NULL response indicates that the named type is correct. Otherwise, the user's response is taken to be the type desired.

tset-m'dialup>300:adm3a'-m'dialup:dw2'-m'plugboard:?adm3a'

To prevent interpretation as metacharacters, the entire argument to -m should be enclosed in single quotes. When using the C shell, exclamation points should be preceded by a backslash (\).

Examples

These examples all use the `-' option. A typical use of
tset in a .profile or .login also uses the -e and -k
options, and often the -n or -Q options as well. These options have
been omitted here to keep the examples short.

Example 1 Selecting a Terminal

To select a 2621, you might put the following sequence of commands
in your .login file (or .profile for Bourne shell users).

set noglob
eval `tset -s 2621`
unset noglob

If you want to make the selection based only on the baud
rate, you might use the following:

set noglob
eval `tset -s -m '>1200:wy' 2621`
unset noglob

Example 2 Selecting Terminals According to Speed or Baud rate

If you have a switch which connects to various ports (making it
impractical to identify which port you may be connected to), and use
various terminals from time to time, you can select from among those
terminals according to the speed or baud rate. In the example below, tset
prompts you for a terminal type if the baud rate is greater
than 1200 (say, 9600 for a terminal connected by an RS-232 line),
and use a Wyse 50 by default. If the baud rate
is less than or equal to 1200, it selects a 2621. Note
the placement of the question mark, and the quotes to protect the >
and ? from interpretation by the shell.

The following entry is appropriate if you always dial up, always at
the same baud rate, on many different kinds of terminals, and the
terminal you use most often is an adm3a.

set noglob
eval `tset -s ?adm3a`
unset noglob

Example 4 Selecting a Terminal with Specific Settings

The following example quietly sets the erase character to BACKSPACE, and kill
to CTRL-U. If the port is switched, it selects a Concept 100
for speeds less than or equal to 1200, and asks for the
terminal type otherwise (the default in this case is a Wyse 50). If
the port is a direct dialup, it selects Concept 100 as the
terminal type. If logging in over the ARPANET, the terminal type selected
is a Datamedia 2500 terminal or emulator. Note the backslash escaping
the NEWLINE at the end of the first line in the example.

Attributes

See Also

Notes

The tset command is one of the first commands a user must
master when getting started on a UNIX system. Unfortunately, it is one
of the most complex, largely because of the extra effort the user
must go through to get the environment of the login shell set. Something
needs to be done to make all this simpler, either the login
program should do this stuff, or a default shell alias should be
made, or a way to set the environment of the parent should
exist.

This program cannot intuit personal choices for erase, interrupt and line kill
characters, so it leaves these set to the local system standards.

It could well be argued that the shell should be responsible for
ensuring that the terminal remains in a sane state; this would eliminate
the need for the reset program.